Metal sheet handling apparatus



Aug. 4, 1959 D. BucclcoNE METAL SHEET HANDLING APPARATUS 4 Sheets-Sheet 1 v Filed June 18, 1957 INVENTOR.

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United States Patent 2,897,952 Patented Aug. 4, 1959 .Cree

METAL SHEET HANDLING APPARATUS Dario Buccicone, Gary, Ind., assigner to Bucciconi Engineering Company, Inc., Gary, Ind., a corporation of Indiana Application June 18, 1957, Serial No. 666,385

18 Claims. (Cl. 198-4`1) This invention relates to the handling of metal sheets and is more particularly concerned with improvements in a method and mechanism for controlling the transfer of sheets from an overhead magnetic conveyor to a bottom conveyor in a high speed processing line.

In the handling of metal sheets in a processing line conveyor employing electromagnets for holding the sheets against a traveling belt are frequently employed. Conveyors of this type are shown in my Patents Nos. 2,642,174, dated June 16, 1953, and 2,527,911, dated October 31, 1950.

It is the usual practice to control the current delivered to the electromagnets in such conveyors by suitable switching arrangements so that the magnetic force acting on the sheets may be reduced or cut olf in order to permit discharge of the sheets from the conveyor. Due to the high speed with which the sheets are delivered by the shear to the processing line, one common conveying arrangement involves delivering the sheets from a fast moving overhead conveyor in the processing line to a slower moving lapping conveyor so that the sheets may be advanced at a lesser rate of speed for deposit in a piling box or for other processing operations. In this arrangement vmagnet switching problems arise which are difficult to solve satisfactorily. It is a general object 4of the invention, therefore, to provide an improved method and means for automatically releasing the sheets fro-m an overhead magnetic conveyor for transfer to a bottom conveyor which makes switching control of the electromagnets unnecessary.

It is a more specific object of the invention to provide a sheet handling apparatus wherein the successive sheets are advanced by an overhead magnetic conveyor for delivery to a bottom lapping conveyor aligned beneath the same and wherein provision is made for releasing the sheets from the overhead conveyor and for dropping the sheets onto the lapping conveyor in overlapped rela* tion without permitting any appreciable lateral shifting of the sheets which would result in scratching or otherwise damaging overlapped portions of the sheets.

It is another object of the invention to provide a sheet handling method and apparatus wherein the sheets are transferred from an overhead rail type magnetic conveyor to a bottom lapping conveyor without any need for switching `of the magnets in the overhead conveyor, with the sheets being released from the holding influence of the magnets by the pressure of air delivered to the top surface of the successive sheets.

lt is a further object of the invention to provide an apparatus for transferring metal sheets from an overhead rail type magnetic conveyor to a bottom lapping conveyor wherein a device is arranged for cooperation with the overhead conveyor which delivers a stream of air upwardly across the path of movement of the sheet so that it is effective to support the sheet until the sheet passes the air stream and thereafter the air is directed onto the top of the sheet with sulicient force to release source of power.

the sheet from the inuence of the magnets and allow the same to drop onto the bottom lapping conveyor.

These and other objects and advantages of the invention will be apparent from a consideration of the method and apparatus which is shown by way of illustration in the accompanying drawings wherein:

Figure 1 is a side elevation, partially schematic, of a sheet handling apparatus having incorporated therein the principal features of the invention;

Figure 2 is a plan View, with portions broken away, of the apparatus shown in Figure l;

Figure 3 is a cross section, on an enlarged scale, taken on the line 3 3 of Figure 1, with portions broken away;

Figure 4 is a horizontal section, on an enlarged scale, taken on line 4 4 of Figure 1;

Figure 5 is a horizontal cross section, on an enlarged scale, taken on the line 5 5 of Figure 1;

Figure 6 is a cross section, on an enlarged scale, taken on the line 6 6 of Figure 2;

Figure 7 is a cross section, on an enlarged scale, taken on the line 7 7 of Figure 2;

Figure S is a side elevation, partly in section and partly schematic, of a modified formv of the apparatus;

Figure 9 is a plan view of the apparatus in Figure 8;

Figure 10 is a view similar to Figure 8;

Figure 11 is a cross section, on an enlarged scale, taken on line 11-11 of Figure 8; and

Figure 12 is a cross section, on an enlarged scale, taken on line 12-12 of Figure 8.

Referring to Figures 1 and 2 of the drawings, there is illustrated an apparatus for handling metal sheets which embodies the principal features of the present invention. In the apparatus shown the sheets S are delivered from a high rspeed processing line to an overhead magnetic conveyor 10 on a feeding conveyor 11, the latter being positioned at the entrance or receiving end of the conveyor 10 and comprising lendless belts supported on the driven pulley 12 and the idler pulley 13. The sheets S are advanced by the overhead conveyor 1t) above a bottom lapping conveyor 14 which is arranged with its receiving end spaced somewhat from the deliveiy end of the feed conveyor 11. The sheets are freed in succession from the overhead conveyor 1t? and deposited on the upper run of the bottom lapping conveyor 14 in lapped relation by operation of an air apparatus indicated at 15 which cooperates with the overhead conveyor 1t) in the delivery ofthe sheets S to the lapping conveyor 14.

The overhead conveyor lil is formed of a plurality of magnetic rail units 16 which are arranged in laterally spaced parallel relation, three of the units being illustrated in the particular arrangement provided. The number of the rail units 16 will depend upon the Width of sheet which is to be handled by the machine. The rail units 16 are of the type disclosed in my Patents Nos. 2,527,911 and 2,642,174. Each rail unit 16 comprises a pair of belt members 17 (Figures l, 2 and 3) arranged on the end pulleys 18 and 19, the former being an idler pulley and the latter Ibeing a driven pulley which is mounted on a cross shaft 2i) having a drive pulley 21 at the one end thereof for connection with a suitable The belt carrying pulleys 18 and 19 are supported at opposite ends of the frame 22 of the unit, the latter being of generally rectangular cross section and extending vertically and longitudinally above the bottom conveyor 14. The frame 22 carries a downwardly opening bottom channel 23 which forms a box for the current from asuitable source.

the belts 17. A topchannel 29 supports the return run of the belts. The electromagnets 24 are spaced lengthwise of the box 23 and thelcoils are connected to a suitable source of current withswitch controlsl being provided for controlling the operation.v of 'the electro. magnets 24, if desired.

The lower or bottom lapping conveyor 14fis preferably of the ,broad belttype such as disclosed in my copending application Serial No. 650,180, filed April 2, 1957. It comprises a pair of sheet supporting belts 30 carried on endpulleys 31 and 32 which are suitably mounted on a supporting framework. The pulley 31. at the receiving end is an idler pulley while the pulley 32 at. the discharge end is supported on a cross shaft 33, whichhas a drive pulley-34 mounted at one end fory connection to a suitable source of power for driving theconveyor. The conveyor 14includes a series of longitudinally spaced magnet units indicated at 35fwhich arel supplied with The magnets 35 -whioh are adjacent the receiving end of the conveyor 14 are of greater-strength and are more closelyspaced than the magnets at the discharge end ofthe conveyor so that the magnetic -force acting on the sheets is greatest-at the point where they are rst dropped onto the conveyor 14 and any shifting ofthe sheets is avoided.

The air apparatus 15 comprises an air tank 36.which Y extends transversely of the apparatus betweenthe discharge end of the feed conveyor 11 and the receiving end of the bottomlapping conveyor 14.4 The tank 36 has an inlet connection at 37 for receiving a pipe or other conduit toconnect the same to an air supply (not shown).

The tank 36 is provided with conduit forming sections 38 :which-are of, generally rectangular cross section and which extend forwardly from the forward Wall 39 of( the tank. The tanksections 38 lare positioned between the lower run of the beltsl 17 on the overhead conveyor ltland theupper run of the bottom lapping conveyor` erally truncated triangular cross section and extending The forward side wall transversely ,of the. apparatus. 39 ofthe air tank 36 is apertured at 41 (Figure 4) to The tubular sections 38 provide passage for the air from the tankv 36-throughthe sections 38. tothe cross member 40. The cross member 40'is provided with two elongate airdischange openings 42 which are located in the space between the center ra1l unit 16 and the two outside rail units,y

The air is delivered across the path of'movement of Y the sheets S and into deector boxes 43V which are .generally rectangular in cross section and which are arranged'in the `space between the rail units 16 with the one end extending overthe cross member 40 as shownv in Figure l. Each deilector box 43 `hasan airl inlet opening 44in the bottom face which is formed at the end s thereof by transversely extending upwardly converging plates 45. The plates 45 have their upper edges spacedV ing or slot .46 in the bottom face formedby downwardlyinclined or converging plates .47 which are spaced at their lower edges to give the slot 46 a tapered formation 1n the longitudinal direction.

The dellector box The air Youtlet slot 46- is closed at the end adjacent the air inlet` slot 44 -by a y bottom apron 48.0n the innermost cross plate 45.v rI`l1e air outlet` slot 46 is tapered towards the other endy of they,y

box 43 `so that air delivered into the box through the inlet orend slot,44` ispassed 'out of the box 43 and.. against the uppermost surface vof thesheets` S throughthe -outlet or longitudinal slot46 withrtheair passage.. belng narrowed down towards the leading...end.of the..

sheets so that the -air pressure isV distributed to apply pressureto the plates S, forcing the same downwardlyA and releasing them from the inuence of the electromagnets 24, less air pressure being needed at the discharge end of the conveyor because of the spacing of the electromagnets.

In operating the apparatus the.electromagnets 24 are supplied with current suicient to produce an electroi magneticforce which will attract .the sheets S and hold them against the lower run of the belts 17 for advance by the upper conveyorl() above the bottom lapping conveyor 14. The sheets S are advanced by conveyor 11 to the entrance end of conveyor 10 where they are gripped by the first electromagnets 24. As the leading end of each sheet S passes the slots or openings 42 it interrupts the stream of air delivered from the tank 36 with the result that the air blows against the lowermost face of the sheet and aids in holding the same against the belts 17 on the conveyor y10.v As the. sheet advances and the trailingedge passes the openings 42, the` air is. delivered through the.y inlet openings 44 .into thedeflector boxes 43 and out throughthedbottom openings 46 where it impinges on the uppermostv surface. ofwthesheet S andapplies sufficient pressure .on thesheet to force it'V downward so thatitadrops.onto the bottom conveyor. 14., The,

electromagnets 35V in the bottom conveyor 14 are'. arranged so that the greatestrforcev is` exerted at the re-V ceiving endof., the conveyor which Vresults inthe-sheets being instantly pulled by the electromagnets against the beltstlfandheld on; the upper run ofthe conveyor withoutanyshifting so as. to avoid. scratching or.otherwise damaging thebottomsurfaceof thesheets as theyare depositedfinlapped relationon the conveyor 14..

A= modified form of 4apparatus embodying the invention. isrillustrated inzFigurcs 8 to.l2 which is particularly.-y

designedto handle the;sheets S wherevit is necessary to arrange the rail units in the. overhead conveyor in relatively. close proximity. Infthis form-of.the.apparatus,

tially identical with the lapping conveyor 14 .in the form ofthe invention previously described, A feed conveyor 53 isepositioned .at the. receiving. end of theconveyors 50 and 52 with the4 ends of the two conveyors S2 and 53 f being spacedA a distance sutcient to accommodate an air apparatus 54.

In this form of the apparatus each. ofthe. rail units 51f of the upper conveyorr 50'` is modified to incorporate thereiny an air deflector means, thereby eliminating, the need for separate air deector boxes. units 51 comprises a pair of belts 5S whichfarey carried onthe. end pulleys 56 and 57', the latterA being supported i oneross shafts 58' and 59 which are in turn supported on f the main frames 60.0f the units. The frame-60fofeach conveyor unit 51 carries a downwardly opening magnet boxor channel 61 (Figures 8, 10, 411 and 12)' in which a series of electromagnets` 62 are mounted in longitudinallyzspaced relation. A belt guide 63 forms the lower faceofthe frame.60V and isprovided with longitudinally extending. parallelrecesses 64 to receivethebelts-SSL The 'magnet box61.of each conveyor .unit51f is closed f' atthedischarge ,end of the .conveyor by a lcurved end portion,.65 andat. the receiving end of the conveyor by thecurved endwportionr, Therstelectromagnet 62: in the box 61 is spaced from the leading end ofthe unit a;sufl`1`cient. distance .to accommodate a horizontally' extending.deflector-plate67 Vwhich, is arranged so that it provides anair inlet slot or opening 68 between its-trail ingor rearmosttedgel and the rear. bottom edge 69 of the end,.portion66, of the magnet box .61 for. receiving air ing 72 positioned below the air inlet slot 63 in the bottom Eachv of the rail Alu; fl A asse/,952

s. face of the box 61 in each of the rail units 51 ofthe conveyor 50. The ,box 61 has openings 73 in its bottom face between the electromag'nets 62 for discharge ofthe air downwardly toward the conveyor 52. Preferably these Iopenings decrease in size toward the leading end of the conveyor 52.

The bottom lapping conveyor 52 is provided with the electromagnet units 74 which are arranged in the same manner as in the bottom lapping conveyor 14 previously described with the greater magnet power being provided at the entrance end of the conveyor to insure that there is suihcient magnetic force exerted on the sheets as they are dropped onto the top run of the conveyor 52 to hold the same against shifting.

In operation, the sheets S are delivered to the overhead conveyor 50 by the feed conveyor 53 and the passage of the leading edge of each successive sheet over the nozzles 72 cuts od the stream of air into the magnet boxes 6l in the conveyor rail units 51 and the air blows against the lowermost surface of the sheet (Figure 8) which holds the sheet against the belts 55 until it reaches the rst of the magnets 62. As the sheet advances the air aids the electromagnets 62 in holding the sheets in contact with the belts 55. As the trailing end of each successive sheet passes the nozzles 72 (Figure 10) the air is delivered into the magnet boxes 6l at the ends 66 of the rail units l and the pressure of the air is exerted downwardly against the uppermost face of the sheet S which has passed the air apparatus 54. This results in the sheet being pulled downwardly away from the induence of the electromagnets 62 for deposit on the lapping conveyor 52.

In bothv forms of the apparatus which are disclosed, the electromagnets in the overhead conveyor are provided with suihcient current to produce a magnetic force which is operative on the sheets to hold the sheets to the conveyor belts but which is not strong enough to hold the sheets against the force of the air when the trailing end of the sheet is moved past the air delivery apparatus and the stream of air is directed into the deilector boxes and caused to impinge upon the uppermost surface of the sheet. lf desired, a switching arrangement may be employed with the electromagnets in the overhead conveyor to shut off the magnetic force and release the sheets and the air may be employed as a supplemental force operating on the top surfaces of the sheets. Ordinarily, the use of the air will eliminate the necessity for any switching control on the electromagnets. The air apparatus may be incorporated in other electromagnetic conveying arrangements which do not involve the use of a lapping conveyor.

While particular materials and speciiic details of construction have been referred to in describing the illustrated forms of the invention, it will be understood that other materials and variations in the details of the apparatus employed may be resorted to.

I claim:

l. A method of handling sheets of magnetic material in a continuous processing line, which comprises delivering successive sheets in a generally horizontal path to a horizontally disposed overhead magnetic conveyor, delivering a stream of air upwardly across the path of movement of the sheets and deflecting the stream of air downwardly against the top surface of each successive sheet as the trailing end of 'the sheet passes the stream of air and'reaches a position in advance thereof for depositing the same on a surface beneath the magnetic conveyor whereby to force the sheet downwardly for release by the magnetic conveyor. V

2. A method of handling sheets of magnetic material in a continuous processing line, which comprises advancing successive sheets in a generally horizontal path to a horizontally disposed overhead magnetic conveyor, directing a stream of air upwardly toward the overhead constream of air and to a position beyond the stream of air for depositing the same on a surface beneath the magnetic conveyor and deflecting the stream of air when the sheet has passed the same onto predetermined portions of the top surface of the sheet to force the same downwardly for release by the magnetic conveyor at the position for depositing the same on said surface.

3. In apparatus for handling metal sheets, a bottom sheet receiving conveyor, an overhead magnetic conveyor extending in aligned relation above the bottom conveyor for delivering sheets to a position above the bottom conveyor for release thereon, an air device at the entrance end of the bottom conveyor having means for delivering a stream of air upwardly across the path of travel of the sheets, and means associated with the overhead conveyor for deflecting the air downwardly against the top surface of the sheet when the sheet has passed through the stream of air whereby to exert downward pressure on the sheet and thereby release the same from the overhead conveyor.

4. In apparatus for handling metal sheets, a bottom conveyor, an overhead magnetic conveyor extending above the bottom conveyoi for delivering sheets to the bottom conveyor, an air tank at the entrance end of the bottom conveyor having an upwardly opening discharge aperture for delivering a stream of air across the path of travel of the sheets, and means forming air deector compartments associated with the overhead conveyor and having downwardly opening receiving and discharge apertures, said air receiving aperture being positioned above the discharge aperture in the air tank and said discharge apertures extending along the overhead conveyor Whereby to permit the air to exert downward pressure on the sheet to release the same from the overhead conveyor when the trailing end of the sheet has advanced beyond the discharge opening in said air tank.

5. In apparatus for handling metal sheets, a bottom conveyor, an overhead magnetic conveyor extending above the bottom conveyor for advancing successive sheets to a position for deposit on the latter, an air supply device at the entrance end of the bottom conveyor having an upwardly opening discharge aperture for delivering a stream of air across the path of travel of the sheets, and means forming air deilector compartments positioned adjacent said overhead conveyor and having downwardly opening receiving and discharge apertures, said air receiving aperture being positioned above the discharge aperture of the air supply device and said discharge apertures extending along the overhead conveyor whereby to cause the air to strike the top surfaces of the sheets and exert downward pressure on the sheets when the trailing ends thereof have advanced beyond the discharge opening of said air supply device.

6. In apparatus for handling metal sheets, a bottom conveyor, an overhead magnetic conveyor comprising a plurality of laterally spaced rail units extending above the bottom conveyor for advancing successive sheets to a position for release on the bottom conveyor, an air device between the opposed runs of the conveyors having an upwardly opening discharge aperture for delivering a stream of air across the path of travel of the sheets, and means forming air deliector compartments positioned between the rail units of the overhead conveyor and having downwardly opening receiving and discharge apertures, said air receiving apertures being positioned to receive air from the discharge aperture in the air device and said discharge apertures extending along the overhead conveyor units whereby to cause the air to strike the top surfaces o f successive sheets and exert downward pressure on the sheets for releasing the same from the overhead conveyor when the trailing ends of the sheets have advanced beyond the discharge opening in'said air device.

7. In apparatus for handling metal sheets, a bottom lapping conveyor, an overhead magnetic conveyor extending in vertically aligned relation above the lapping conveyor for delivering sheets to a position above the 7. lapping conveyor for releasee'th'ereon, an 'air tank-at the entrance end ofthe Alapping conveyorahavingI an--up' wardly directed air discharge 'means Afor delivering' a stream of air across the path'of travelof` the sheets-and" meansforming air deflector compartments associatedwith the overhead conveyor and having downwardly opening air receiving and discharge apertures, said air-receiving apertures being positioned toY receive' air-from the* air tankand said discharge-apertures extendingA alongV the overhead conveyor whereby to cause the air to .exert downward pressure on the sheet tof release the same from the overhead conveyor when the trailing end of the'sheet' has. advanced beyond the discharge' meansin said air tank.

8.-In apparatus for handling metal sheets, a bottom conveyor, an overhead magnetic conveyor comprising a plurality of relatively narrow laterally spaced elongate conveyor units extending above the bottom conveyor for advancing successive sheets to. a position for release on the bottom conveyor, anv air device between the opposed runs of the bottom and overhead conveyors having an upwardly opening discharge `aperture for delivering a stream of air across the path of travel of the sheets, and

means forming air deector compartments associated with the overheadL conveyor units and having openingsV formf charge apertures decreasing in size ltoward the leading,V

end of the overhead conveyor.

10. In apparatus for handling metal sheets, a bottom conveyor, an overhead magnetic conveyor having a series of laterally spaced relatively narrow elongate conveyor units extending above the bottom conveyor for delivering sheets to a position for depositen the bottom. conveyor,

an air supply device adjacent the entrance. end of the bottom conveyor having meansfor deliveringa stream of.

air upwardly across the path of travel of the sheets, and

means forming air deiiector compartments in therover-A head conveyor units, said means having air receiving and discharge apertures, said air receiving aperturebeing positioned to receive the air from the supply device and.

said discharge apertures extending along the overhead conveyor units whereby the air is deflected downwardly from said compartments against the top of the sheet to force the same downwardly from the overhead conveyor. when the trailing end of the sheethas advanced beyond.y

the stream of air from said supply device.

11. In apparatus for handling metal sheets, a bottom conveyor, an overhead magnetic conveyor extending above the said bottom conveyor for delivering sheets to a position for release on said bottom conveyor, said over.- head conveyor compiising an elongate downwardlyfopeningbox for receiving therein longitudinally spaced magnets and a traveling belt having the lower sheet engaging run .traveling below the magnets, means covering the lower face of said box and having air receiving and dis.--

charge openings therein, an air supply device adjacent the entrance end of the bottom conveyor having anopening for delivering a stream of air. upwardly across the path of travel of the sheets, said overhead conveyor being.

positioned with its air receiving opening abovethe open.- ing in the Vair supply device and with the air discharge openings. extending along saidlbottom conveyor whereby to'cause the air to exert downward pressure on the sheet to release the same from the overhead conveyor magnets when the trailing end of the sheet has advanced beyond theopening in'said air supply device.

12. In'apparatus vfor handling metal sheets, a bottom conveyor, an overheadmagnetic conveyor extending vin vertically aligned'relation above'the bottom conveyor for deliveringsheets to' a positionfor deposit on-l the'bottom' A relatively narrow elongate conveyor units arranged in parallel' laterally spaced relation, anl air supply'device conveyor," said overhead conveyor comprisingaseries'of* adjacent 'the entrance end of the bottom conveyor-'having v` a .discharge aperture'for delivering a stream-ofair upwardly across thev path of travel of the sheets, and compartmcnt forming boxes arranged between theunits of said overhead 'conveyor and having air receiving and"L discharge apertures, said 'air receiving aperture being' positioned for receiving the air from the supply deviceA and said discharge apertures extending' along the bottom faces of said boxes whereby to cause the air to strike the top'surfaces of the sheets and force the sanne from the overheadv conveyor when the trailing ends of the sheets have advanced beyond the discharge aperture ofl said air supply device.

13. 'In' apparatus for handling metal sheets,'an"over'' head magnetic conveyor unit comprising. an elongate downwardly opening compartment forming magnet box having a series of electromagnets mounted in longitudinallyA spaced relation therein, a sheet carrying belt and' l a guide shoe for said belt closing the bottom face of said magnet box, an air receiving aperture at the trailing end of said magnet fbox and a series of air discharge apertures spaced along said guide shoe, an air supply device adjacent the entrance'end of said conveyor unit having anI aperture for delivering a stream of air across the path of travel of the sheets and into the air receiving opening in said magnet box whereby to direct the air onto the y upper surface of the sheet to release the same from the iniiuence ofthe magnets when the trailing end of the sheet has advanced beyond the opening in said air supply device.

14. In apparatus for. handling sheets of magnetic maf terial wherein the sheets are advanced in a generally.

horizontal plane while held against the lower mn of a traveling belt by electromagnetic force, a magnetic rail type conveyor unit which comprises a magnet box having its ends closed and a belt guiding shoe in the lower face j thereof, a belt traveling in said guide shoe, a series of force on a sheet engaged with the lower face of said belt, said belt guide having an` air receiving opening at the entrance end of said unit and air discharge openings spaced therefrom .in the direction of advance of said belt.

15. A sheet handling apparatus comprising an overhead conveyor having sheet engaging traveling belts and electromagnets .arranged to hold the sheets against the belts, one or-.more air -deector boxes associated with the conveyor and having openings for receiving air adja- "cent the trailing end thereof and for discharging the air downwardly against the sheets in areas in advance of the same, and an air supplydevice for delivermg a1r across the path of travel of the sheets and into an air receiving opening in each deector box.

16. A sheet handling apparatus comprising an overhead conveyor having laterally spaced endless belts and electromagnets arranged to hold the sheets against the lower lfaces of the belts, means forming air deector boxeszarranged between the belts with air discharge apertures opening downwardly along the same, the air discharge apertures being arranged to deflect the air against the uppermost surfaces of the `sheets vfor forcing'them `electromagnets in said `box for exerting electromagnetic downwardly away from the pull of the electromagnets and means to deliver air to the deilector boxes in timed relation to the movement of the sheets.

17. A sheet handling apparatus comprising an overf head conveyor having a sheet engaging traveling belt and electromagnets arranged to hold a sheet against the v belt, an air deector box associated with 'the conveyor and having an opening foi-receiving air `adjacent the trail'- 9 ing end thereof and for disc/hanging the air downwardly against the top surface of the `sheet thereby [forcing the sheet downwardly away from the pull of the electromagnets, and an air supply `device for delivering air upwardly across the path of travel of the sheet as it advances bei. heath said traveling belt and into the air receiving open- 10 'wardly against the top surface of the rsheet when the trailing end of the sheet advances beyond the upwardly `directed stream of air thereby to force the sheet downwardly away from the pull of t-he electromagnets.

References Cited in the file of this patent UNITED' STATES PATENTS 2,168,419 Paterson Ang. 8, 1939 2,261,970 Matthews Nov. 11, 1941 2,312,357 Odquist Mar. 2, 1943 2,642,174 Buccicone June 16, 1953 FOREIGN PATENTS 750,824 Great Britain June 20, 1956 

